It has been conventionally known that a dip molded article for use in contact with the human body, such as a nipple, an air ball, a glove, a balloon and a sack, is obtained by dip molding of a latex composition containing a latex of natural rubber. A latex of natural rubber, however, contains a protein causing an allergy symptom in the human body, and thus is problematic in terms of use in a dip molded article that is in direct contact with the mucous membrane or organs of a living body. Therefore, studies about use of not a latex of natural rubber, but a latex of synthetic polyisoprene or styrene-isoprene-styrene block copolymer have been increasingly made (Patent Document 1).
For example, Patent Document 1 discloses a composition for dip molding, containing a latex of synthetic polyisoprene and/or a styrene-isoprene-styrene block copolymer having a weight average molecular weight of 10,000 to 5,000,000, and a sulfur-based vulcanizing agent and a vulcanization accelerator. According to the composition for dip molding described in Patent Document 1, a dip molded article reasonably improved in tensile strength is obtained. Tensile strength not sufficient, however, may be caused depending on the intended use, and a further improvement in the tensile strength has been thus demanded.